1. Field of the Invention
The present invention relates to marine propulsion systems, in particular, the present invention relates to a marine propulsion system including an engine.
2. Description of the Related Art
Conventionally, marine propulsion units (marine propulsion systems) including an engine are known (for example, see JP-A-Hei 9-263294). JP-A-Hei 9-263294 discloses a marine propulsion unit including an engine and a power transmission mechanism transmitting driving force of the engine to a propeller in a predetermined and fixed reduction ratio. The marine propulsion unit is arranged in a manner such that the driving force of the engine is directly transmitted to the propeller via the power transmission mechanism and the rotational speed of the propeller increases proportionally with respect to the engine speed as the engine speed increases.
However, the marine propulsion unit (marine propulsion system) disclosed in JP-A-Hei 9-263294 has a problem in that it is difficult to improve acceleration performance in a low speed position in the case that speed reduction ratios of the power transmission mechanism are set to gain a larger maximum speed. Conversely, there is also a problem that it is difficult to gain a larger maximum speed in the case that the reduction ratios of the power transmission mechanism are set to improve the acceleration performance in the low speed position. In other words, the marine propulsion unit disclosed in JP-A-Hei 9-263294 has a problem in that it is difficult to satisfy both acceleration performance and maximum speed to a user's desired level.